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Don't evaluate DACs solely on the basis of SINAD. DSP Headroom: Don't underestimate the importance of DSP headroom. This is not shown in any of Amir's tests, because he is not currently testing for DSP clipping caused by intersample peaks exceeding 0 dBFS. DACs should be tested with a +3.01...

Thank you for purchasing a DAC3 B. The DAC3 B does not have a volume control and the unbalanced RCA output is calibrated to exactly 2.0 Vrms at 0 dBFS. Units such as the DAC3 HGC and DAC3 L have volume controls that allow you to set the output at higher or lower levels. On the DAC3 HGC and...

Many popular Analog Devices DSP chips have internal dedicated fixed-point ASRC resources on all of the digital inputs. These do not have to be turned on, but many developers choose to use them because they allow a constant sample rate in the DSP core. Filter coefficients can be set up once and...

Yes, I agree. With most square wave frequencies that I can generate with my APx555, I see the onset of interpolator overload distortion when the unfiltered square wave is between -2.100 dBFS (distorted) and -2.115 dBFS (clean). This threshold agrees with your calculations. For this hardware...

Unfiltered square waves produce a 3.01 dB overshoot when reconstructed. They can easily be generated with the APx555 test stations. I have been using these square waves and a +3.01 dBFS fs/4 sinewave. I created the sinewave using Audacity. I have just published another application note on this...

This is incorrect. The "clipping" does not produce harmonic distortion because the waveform is not clipped in the traditional sense of the word. This is not a waveform clipping problem, it is a filter overload problem. The interpolation filter fails to operate properly when the taps are...

Here is another issue that we have not discussed on this thread: One effect of overloading the interpolation filter is that this overload destroys the stopband attenuation of the brick wall filter. Start at 45 min into the video to get some context, and then take a look at the FFT shown at...

Several contributors have provided examples of CDs and tracks that show extreme examples of true peak values that are well over 0 dBFS and, in many cases, over +3 dBFS. Thank you for this information. Are any of you able to provide statistics for your entire music library, or point me to such a...

We discovered this issue while designing the DAC2. We made changes to the gain structure of the DAC2 before its release in 2012. It was too late to do anything about the DAC1. The DAC1 was released in 2002, long before we were aware of the issue. DAC1 production ended in 2012 when the DAC2 was...

You are correct, removal is easy, but the unit should not be opened by persons that are not fully-qualified to service electronic equipment. Dangerous high voltages can persist on the internal capacitors for several minutes after the removal of the AC power cord, even if the unit was turned off...

Here is an example of a DAC that has a 0 dBFS+ inversion problem: +1dB Intersample Overs Test - Denafrips Pontus 2 (12th Anniversary Edition)

@tmtomh, Thanks for the waveform plot! Some DACs have this exact same problem when they encounter a 0 dBFS+ event. These DAC make that same "very audible click/tick" sound whenever a 0 dBFS event occurs. This is one reason why ASR should test for 0 dBFS+ performance. Sadly, these egregious DSP...

Here is the system noise performance of various Benchmark Systems: The green curve is the AHB2 power amplifier running in stereo mode with the inputs shorted. This is the output noise of the amplifier with no noise from any upstream devices. The horizontal axis is the volume control setting...

I have only run tests on mp3 codecs. The mp3 decoder adds many intersample peaks above 0 dBFS. Try this: Rip some CDs using various lossy formats and then decode them back to 44.1/16 PCM. With the mp3 codec you will see a big increase in overs. I don't know what happens with other lossy...

On the DAC3 HGC the headphone volume and line volume are both controlled by a single volume knob. The DAC is set to maximum volume (line and headphone) when the HT mode (home theater bypass mode) is active. This volume control bypass is intended for applications where the volume is controlled...

This is not a mistake in production, it is a mistake in the playback hardware. We didn't have this problem until oversampled DACs were invented. At worst, the analog output stage of a non-oversampled DAC will flat-top clip the peak. Most early DACs actually had the headroom to reproduce the...

I believe the AK4493 places the digital volume control in front of the interpolator. The ESS places it after the interpolator. Turning the digital volume down inside the ESS does not add headroom. The digital level must be turned down before sending the signal to the ESS. It must also be turned...

If you were testing cars, would you just test for horse power and torque but not actually drive the car above 60 MPH? If something really bad happens at 70 MPH, your readers would want to know about it. This is especially true when all of your readers would reasonably be expected to drive at...

The assumption that "a huge amount of music ... doesn't have this problem" is incorrect. The vast majority of 44.1 kHz recordings have intersample peaks that exceed 0 dBFS. Curiously, tracks with minimal compression can have some of the highest and most frequent intersample peaks. See my...

The HPA4 would optimize the gain staging between your DAC and the internal THX 888 headphone amplifier. The SNR and THD+N of the HPA4/LA4 input stage is nearly constant over a very wide range of input gain settings. This allow the use of a 4 Vrms consumer-grade device or a +24 dBu...